Conventionally, a typical water purifier mounted to a tap water faucet for home or commercial use is composed of a water purifier main body having a raw water inlet and a raw water outlet, and a filtration portion for holding a filtration material that purifies raw water by filtration. The most popular type of water purifier in recent years can maintain filtration performance at or above a predetermined level while saving a space by employing a compact filtration portion holding a small quantity of the filtration material that is replaced each time it has been used for filtration of a predetermined volume of water.
The water purifier having the above-described structure needs a mechanism that enables a user to attach the filtration portion to the water purifier main body easily in a secure manner so as not to cause a water leak or the like. In other words, in the case of a water purifier for home use, in particular, the user prefers a water purifier with a time-and-labor saving structure that makes the water purifier easy to attach for anyone by omitting a burdensome step, such as referring to the manual in each replacement.
Water purifiers disclosed in Japanese Laid-open Patent Application No. 116656/1995 (Tokukaihei No. 7-116656) and Japanese Laid-open Patent Application No. 128911/1999 (Tokukaihei No. 11-128911) are known as examples of the water purifier equipped with the compact filtration portion.
FIG. 12 is a view schematically showing a structure of a water purifier 60 disclosed in the above-cited publications. As shown in the drawing, the water purifier 60 disclosed in the above-cited publications is provided with a bayonet mechanism 63 at a connection portion of a water purifier main body 61 and a filtration portion 62.
The following description will describe more in detail the conventionally used bayonet mechanism 63. As shown in FIG. 12, the bayonet mechanism 63 is chiefly composed of a cylindrical concave portion 65 provided to a raw water outlet 64 formed at the side portion of the water purifier main body 61, and a convex portion 66 provided to the filtration portion 62 so as to correspond with the concave portion 65.
The concave portion 65 is provided with a pair of notch portions 67 and a pair of concave portion side overhang portions 68 extending in the circumference direction on the inner circumference surface at an opening end portion.
On the other hand, the cylindrical convex portion 66 that can be inserted into the concave portion 65 is formed at a raw water inlet 69 of the filtration portion 62. The convex portion 66 has a diameter slightly smaller than the interior diameter of the concave portion 65 defined at the tip end portion of the pair of the concave portion side overhang portions 68. The convex portion 66 is provided with a pair of convex portion side overhang portions 71 on the outer surface at the tip end. The overhang portions 71 are formed so that they are respectively allowed to go into the pair of notch portions 67 formed on the inner circumference surface of the concave portion 65.
According to the above arrangement, the convex portion 66 is inserted into the concave portion 65, and then the both are displaced relatively to each other around the coaxial core, whereby the water purifier main body 61 and the filtration portion 62 are coupled to each other. In other words, the concave portion side overhang portions 68 and the convex portion side overhang portions 71 are engaged with each other at their respective opposing surfaces. Also, according to the above arrangement, by displacing the convex portion 66 and the concave portion 65 relatively to each other in a direction opposite to the engaging direction, the concave portion side overhang portions 68 and the convex portion side overhang portions 71 are spaced apart from each other, thereby allowing the filtration portion 62 to be detached from the water purifier main body 61.
To be more specific, as shown in FIG. 12, the surfaces of the convex portion side overhang portions 71 that engage with the surfaces of the concave portion side overhang portions 68 are tilted toward the axial direction, which not only makes relative displacement of these components toward the axial direction smooth, but also improves engaging adhesion to each other. The convex portion side overhang portions 71 are provided with stoppers 72 at the end portions for regulating relative displacement of the convex portion 66 and the concave portion 65 around the coaxial core. When the end portions of the concave portion side overhang portions 68 are stopped by the stoppers 72, the overhang portions 68 and 71 are engaged with each other, and the tip end surface of the convex portion 66 presses against a seal member 70, whereupon the convex portion 66 and the concave portion 65 are engaged with each other fluid-tight.
Further, the bayonet mechanism 63 is provided with an unillustrated seal member fall-off stopping portion on the inner circumference surface of the concave portion 65 so as to ensure the coupling condition during the engagement and to prevent a water leak or the like. Also, the seal member 70 is provided with an unillustrated step portion at the outer circumference, and the step portion is stopped by the seal member fall-off stopping portion, which prevents a fall-off of the seal member 70.
Next, the following description will describe a connection operation of the bayonet mechanism 63 with reference to FIG. 12. Initially, in order to couple the filtration portion 62 to the water purifier main body 61 that is immovably attached in an upright position, as shown in the drawing, the convex portion side overhang portions 71 of the convex portion 66 provided to the filtration portion 62 need to be inserted into the notch portions 67 of the concave portion 65 provided to the water purifier main body 61. Hence, in a first step, the filtration portion 62 is rotated around the axial core so that the longitudinal direction of the filtration portion 62 becomes in parallel or almost in parallel with the horizontal direction, under which condition, the convex portion side overhang portions 71 are inserted into the notch portions 67 provided to the water purifier main body 61.
Then, as a second step, the filtration portion 62 is rotated counterclockwise by approximately 90° when viewed from the water purifier main body 61. This allows the concave portion side overhang portions 68 to go into a space between a convex portion principal surface 73 and the convex portion side overhang portions 71 of the filtration portion 62, and the water purifier main body 61 and the filtration portion 62 are coupled to each other fluid-tight when the end portions of the concave portion side overhang portions 68 touch the stoppers 72. At this point, the longitudinal direction of the filtration portion 62 is vertical.
According to the conventional water purifier discussed above, however, the operation to engage the filtration portion 62 with the water purifier main body 61 involves the first and second steps with no exception, which poses a problem that the attachment job is time-consuming. In other words, in the case of inserting the convex portion side overhang portions 71 into the notch portions 67 of the concave portion 65 provided to the water purifier main body 61, if the position of the filtration portion 62 with respect to the immovably attached water purifier main body 61 is determined incorrectly, merely an inserting operation takes a long time. Moreover, the user has to pay attention to a rotational direction of the filtration portion 62. Hence, the conventional water purifier has a problem that it unexpectedly demands time-consuming operations.
Also, according to the conventional water purifier as described above, the convex portion 66 and the concave portion 65 are engaged with or spaced apart from each other by inserting the former into the latter and displacing the both relatively to each other around the axial core. Hence, in case that a stream of water with a high water pressure flows in sporadically, a pressure may possibly be applied in a direction around the axial core. In such a case, if the pressure applying direction is a direction in which any movement is regulated by the stoppers 72 (a rotational direction that generates a spaced apart condition), the water purifier main body 61 and the filtration portion 62 are spaced apart from each other, which causes the filtration portion 62 to fall off. Hence, the conventional water purifier has a problem that there is a likelihood that the filtration portion falls off when a stream of water with a high water pressure flows in sporadically.
On the other hand, in terms of management for sanitation of a water purifier equipped with a compact filtration portion, there has been a demand for a function of notifying the user of a service life unique to each filtration material, that is, the time of replacement of the filtration material. For example, a PID (Performance Indication Device) or the like is known as an example of an accessory device for the water purifier furnished with such a function.
Water purifiers disclosed in U.S. Pat. Nos. 5,928,504 and 5,888,381 are known as examples of a mechanism of notifying the user of the time for replacement of the filtration material by the PID or the like.
For example, U.S. Pat. No. 5,928,504 supra discloses a mechanism for mechanically accumulating a total volume of raw water that has been filtered, and a valve mechanism for stopping an incoming flow of raw water when a predetermined volume of raw water has been filtered, etc.
According to the mechanisms disclosed in the above-cited publication, a turbine is provided in a channel for raw water flowing through a cartridge, and the turbine is rotated by a stream of water while a rotational speed of the turbine is lowered as needed by a plurality of gears connected to the turbine, whereby a total volume of raw water passing through the cartridge is accumulated mechanically.
However, in order to accumulate a total volume of water by the mechanical method using the mechanisms described in the above-cited publication, it is necessary to provide a rotary mechanism composed of a combination of a turbine, a plurality of gears, etc. inside the cartridge, which undesirably increases the cartridge itself in size, thereby posing a problem that it becomes difficult to save a space.
On the contrary, there has been disclosed a mechanism that notifies the time of replacement of the filtration material not by directly accumulating a total volume of raw water that has been filtered, but by accumulating time while raw water is filtered (filtration time) with an electric circuit. For example, a water purifier disclosed in U.S. Pat. No. 5,888,381 supra has an arrangement, in which the vicinity of an end cap of the filtration material is sealed airtight with a flexible cap having a diameter slightly larger than that of the end cap, and a substantially S-shaped conductive arm provided to the outside of the flexible cap is directly attached.
The conductive arm is arranged in such a manner that, when an internal pressure in the flexible cap rises with filtration by the filtration material, the conductive arm amplifies the internal pressure in the flexible cap, so that the tip end of the conductive arm is brought into contact with the electric circuit.
In other words, according to the above arrangement, water fills in a space between the flexible cap and the filtration material and the internal pressure keeps rising during filtration, which expands the flexible cap and causes the tip end of the conductive arm to move toward the electric circuit to be brought into contact with an input portion of the electric circuit. In this manner, the water purifier disclosed in the above-cited application accumulates filtration time by closing the electric circuit inside the cartridge.
However, the cartridge using the flexible cap conveys a change in water pressure inside the cartridge to the outside by means of the flexible cap. Accordingly, not only a metal conductive arm for amplifying a change in water pressure, but also a connecting member for the conductive arm have to be used. For this structural reason, the conductive arm and the electric circuit board are exposed and the indicator portion and the cartridge portion will not be fluid-tight. This poses a problem that there is a high risk that the user may erroneously wet the electric circuit board when he replaces the cartridge.
Also, the method using the flexible cap as described above utilizes flexibility of the overall flexible cap. Hence, there is a problem that materials of the flexible cap are limited to those having flexibility at or above a certain level. In addition, in order to readily amplify a change in water pressure, each of the members, such as the flexible cap and the conductive arm, have to be increased in size. This makes it difficult to save a space, and increases the number of components, and hence the manufacturing costs.